4. Cancer Comorbidities and Complications: An Ever-Growing Challenge Demanding Focus

Further to the range of physical and psycho-social challenges resulting from their cancer and cancer treatment, cancer patients and survivors may also be faced with distinct health conditions in parallel to their cancer journey, in the form of comorbidities and complications. Comorbidities are defined as the co-existence of long-term health conditions in the presence of a primary disease of interest, while complications correspond to health conditions resulting from this primary disease or from its treatment^92,93.

Owing to shared risk factors, average age of patients as well as to systemic impacts of disease and treatment, comorbidities and complications are particularly common in cancer patients and represent a highly significant and increasing burden for healthcare and social welfare systems^94,95. Research shows that the majority of cancer patients, even up to 90% depending on age and cancer type, report at least one comorbid condition^96,97. Such comorbidities and complications are very diverse, and can typically include pulmonary disorders, diabetes, obesity
and dietary disorders, cardiovascular diseases such as heart failure, myocardial infarction, arrhythmias, hypertension and thrombosis, stroke, liver diseases, neurological and mental health disorders^98,99.

Comorbidities and complications can have a dramatic impact on cancer patient’s prognosis for their tumour, as well as on their overall survival and long-term quality of life. In addition to being responsible for potential delays in cancer diagnosis, such conditions may cause affected patients to suffer higher levels of toxicity from cancer treatment and can prevent optimal cancer treatment. Owing to lack of consensus on how to record, interpret or manage cancer comorbidities and complications, patients with relevant comorbidities are also less likely to receive cancer treatment with curative intent. They are also often excluded from randomised clinical trials, further reducing their chances of survival¹⁰⁰. Consistently, data clearly indicates a higher mortality in cancer patients affected by comorbidities and complications¹⁰¹, as well as a strong association with indicators of poorer quality of life, including nutritional status, physical functioning, general health and pain^102,103.

As a result of lack of recognition of the issue and typically siloed organisation of health systems¹⁰⁴, there are still significant gaps in all aspects of the management of cancer comorbidities and complications in Europe. This includes the prevention of comorbidities and complications in cancer patients and survivors through health promotion, the detection of these conditions, the assessment of the risk of cancer patients to develop them, as well as the provision of adapted treatment and care to address them¹⁰⁵. This also relates to the many patients treated for a chronic severe disorder who develop cancer as a second life-threatening disorder.